greenplumn CXformCollapseProject 源码
greenplumn CXformCollapseProject 代码
文件路径：/src/backend/gporca/libgpopt/src/xforms/CXformCollapseProject.cpp
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2015 VMware, Inc. or its affiliates.
//
// @filename:
// CXformCollapseProject.cpp
//
// @doc:
// Implementation of the transform that collapses two cascaded project nodes
//---------------------------------------------------------------------------
#include "gpopt/xforms/CXformCollapseProject.h"
#include "gpos/base.h"
#include "gpopt/operators/CLogicalProject.h"
#include "gpopt/operators/CPatternLeaf.h"
#include "gpopt/operators/CPatternTree.h"
using namespace gpopt;
//---------------------------------------------------------------------------
// @function:
// CXformCollapseProject::CXformCollapseProject
//
// @doc:
// Ctor
//
//---------------------------------------------------------------------------
CXformCollapseProject::CXformCollapseProject(CMemoryPool *mp)
: CXformExploration(
// pattern
GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CLogicalProject(mp),
GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CLogicalProject(mp),
GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CPatternLeaf(mp)), // relational child
GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CPatternTree(mp)) // scalar project list
),
GPOS_NEW(mp) CExpression(
mp, GPOS_NEW(mp) CPatternTree(mp)) // scalar project list
))
{
}
//---------------------------------------------------------------------------
// @function:
// CXformSplitDQA::Exfp
//
// @doc:
// Compute xform promise for a given expression handle;
//
//---------------------------------------------------------------------------
CXform::EXformPromise
CXformCollapseProject::Exfp(CExpressionHandle & //exprhdl
) const
{
return CXform::ExfpHigh;
}
//---------------------------------------------------------------------------
// @function:
// CXformCollapseProject::Transform
//
// @doc:
// Actual transformation to collapse projects
//
//---------------------------------------------------------------------------
void
CXformCollapseProject::Transform(CXformContext *pxfctxt, CXformResult *pxfres,
CExpression *pexpr) const
{
GPOS_ASSERT(nullptr != pxfctxt);
GPOS_ASSERT(nullptr != pxfres);
GPOS_ASSERT(FCheckPattern(pexpr));
CMemoryPool *mp = pxfctxt->Pmp();
CExpression *pexprCollapsed = CUtils::PexprCollapseProjects(mp, pexpr);
if (nullptr != pexprCollapsed)
{
pxfres->Add(pexprCollapsed);
}
}
// EOF
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